The HAM network is almost completely self policed.
I think this is confusing "mostly well behaved" with self policed. For instance, look at the abject fuckery that goes on at 14.313 MHz each and every day. All manner of rule violations. Not judging the rules here, but no question, deep and serious violations of them. No one "polices" this in any sense of the term; nothing any ham does shuts it down, slows it down, restrains it, or otherwise serves as a "police" function. Reporting it to the FCC does nothing; years and years of reports have gone without any response.
Now, it's quite true that most hams don't take part, and further, view the situation as appalling; but this is like your neighbor disliking seeing crack sold on the sidewalk. That's behaving well, not policing. They're not policing it; they might report it, but that's still not policing it. Only the police can do that, because they have the authority and power to do something about it. In the ham situation, the feds aren't coming when they are called, either, so the activity goes unchallenged in any realistic way. And believe me, getting on there and arguing? Not helpful.
There's more than that going on, too. I know for a fact that there are stations on the air using considerably more than legal power; stations that intentionally interfere with others in several ways, etc. I *also* know that the FCC has the analytical tools to detect, and the authority to stop, this kind of behavior. I lay the blame for this shameful garbage entirely at the FCC's feet.
Allowing encrypted traffic would allow me to sell internet service to people in rural areas because there's no way to detect what is in the encrypted content.
Yes, but any ham can do the same thing for free. Encrypted or not. That's going to make your business model unsustainable. Also, I should point out that packet has allowed email back and forth to the Internet for decades now. So I think your idea of "providing Internet" isn't going to choke the spectrum. Hard to sell something others give away for free (not impossible... but hard.)
Another thing: With the plethora of digital modes available right now, it's become a royal PITA to try and figure out what you're listening to, much less decode it. Is it Olivia? RTTY? Amtor? Heil? Packet? and on and on for must be over a hundred modes and variants. The difference between an encrypted packet and one you can't figure out otherwise is... nothing.
And one more thing (lol): As far as HF goes, we don't have the bandwidth to supply anything like Internet to anyone. There's no risk whatsoever of commercial interest of that type coming in. You'd have to be talking about operation at UHF and above, and *that* means line of sight, and *that* means latency that grows with every link, and it also means that those 99.99% dead bands would see some use, which might keep them from being taken from us. Not a perfect reason by any means, but a reason regardless. The fact is, cellphones have almost entirely killed VHF/UHF ham activity. It's sad as hell, but there it is.
Oh, hey. One MORE thing: Your "Internet supply" is going to have to accept all manner of interference from other hams, etc. That's going to make your service really, really poor. Quite aside from the free competition that will start up the day after you do because you're going to offend every ham with half a wit.